That puts the minimum absolute cost if you launched 2 a year at not less than $1B each launch. At 1 per year it is about $1.4B each launch. But in budget for the year launching two in 1 year requires a budget of $2B but launching only 1 a year requires only a budget of $1.4B.

That puts the minimum absolute cost if you launched 2 a year at not less than $1B each launch. At 1 per year it is about $1.4B each launch. But in budget for the year launching two in 1 year requires a budget of $2B but launching only 1 a year requires only a budget of $1.4B.

That's before payload, of course. Add an Orion and a ride-share DSG module each time for typical budgets.

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"If we shared everything [we are working on] people would think we are insane!"-- SpaceX friend of mlindner

That puts the minimum absolute cost if you launched 2 a year at not less than $1B each launch. At 1 per year it is about $1.4B each launch. But in budget for the year launching two in 1 year requires a budget of $2B but launching only 1 a year requires only a budget of $1.4B.

That's before payload, of course. Add an Orion and a ride-share DSG module each time for typical budgets.

It's the allowed budget level that is the real problem for SLS.

The budget would probably never get as high as $1.5B / year just for the SLS LV line and any more than the $800M / year for ground support. That gives a total of not more than $2.3B which must also handle upgrades and future development costs. If launching 1 per year there is enough remaining to do significant development work for upgrades ~$900M but launching at 2 per year development upgrades is starved.

But if you also consider Orion costs + DSG payloads and budget with this added to the total and the likely hood of all things SLS/Orion/GSE/DSG budget capped at no higher than $3.5M, that $900M margin disappears quickly in order to develop and build the DSG elements and for making improvements to the SLS/Orion and after EM-2 shouldering the complete cost of the SM manufacture for Orion.

The difficulties have only just begun for the program if the costs have grown for the basic incremental costs. Initially SLS's incremental cost was supposed to be (less EUS) ~$300M but with just engines costing $55M each for total of $220M that figure may be difficult to reach! Which will starve payload (DSG) development and ultimately SLS's purpose for being.

SLS 1B = not less than $501M (NOTE this is a very optimistic estimate)

This also shows why NASA is looking at ways to cut incremental costs of the EUS by using a different cheaper engine. A pair of BE-3U's ($8M each, this actually is a high estimate and reality is likely to be lower) could save as much as $60M.

So was wondering why SLS kept the clean-pad design of the Ares I ML and tower vs moving the FSS to the Pad surface like Shuttle. The clean pad made sense for Ares as you had two separate LVs, but with SLS after EM-1/only Block 1A flight the vehicle should have a fixed height for umbilicals. By removing the Tower from the ML you free up a lot of space and most importantly weight on it.

So was wondering why SLS kept the clean-pad design of the Ares I ML and tower vs moving the FSS to the Pad surface like Shuttle. The clean pad made sense for Ares as you had two separate LVs, but with SLS after EM-1/only Block 1A flight the vehicle should have a fixed height for umbilicals. By removing the Tower from the ML you free up a lot of space and most importantly weight on it.

The original concept was to have a shared pad with commercial launcher(s). That seems to be on indefinite hold.

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"If we shared everything [we are working on] people would think we are insane!"-- SpaceX friend of mlindner

So was wondering why SLS kept the clean-pad design of the Ares I ML and tower vs moving the FSS to the Pad surface like Shuttle. The clean pad made sense for Ares as you had two separate LVs, but with SLS after EM-1/only Block 1A flight the vehicle should have a fixed height for umbilicals. By removing the Tower from the ML you free up a lot of space and most importantly weight on it.

because it would increase pad time. integration off pad with the umbilical tower makes more sense like Atlas V and Falcon 9. The upper stages and spacecraft need to be checked out with the umbilicals. Spacecraft need to be connected to GSE once attached to the rocket.Shuttle umbilicals were at the tail. LH2 vent was the only connection at the pad.

Right, and the assembled whole is always more than all the pieces separately.

SLS is simply expensive. Just the hardware is expensive.

There's a way around this: Make SLS reusable. Flyback boosters AND the core. I'm aware of one such recent proposal, but it went nowhere, not even a pre-phase-A study.

(To make this feasible, it may be necessary to stretch the upper stage.)

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Chris Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Right, and the assembled whole is always more than all the pieces separately.

SLS is simply expensive. Just the hardware is expensive.

There's a way around this: Make SLS reusable. Flyback boosters AND the core. I'm aware of one such recent proposal, but it went nowhere, not even a pre-phase-A study.

(To make this feasible, it may be necessary to stretch the upper stage.)

Getting Orion to a space station in low lunar orbit may also require a stretched upper stage.

Low lunar orbit isn't a very good place for a space station, tho.

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Chris Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Flyback core? No - not that and have maximum payload delivery. I would agree that in a perfect world; the boosters would be flyback LOX/Hydrocarbon, the corestage would have 5 and not 4 RS-25's and the upper stage would have stronger engines and a slightly higher propellant load.

But that's not what we're getting. For better or worse, SLS is not going to be changing much.

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